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Since the 80's there have been a lot of changes to the bikes geometry . . . for example a lot of bike in the mid to late 80's has seat and head tubes 74 parallel. A 54cm frame will have a 54cm top tube (54 Square). You get the idea. I mean now we have soem road bikes that have 71 degeee head tube angle, and it would be rare, if you could find it at all back in the 80's.

Things alway evolve or change. My question is what is causing the change? . . . . What is the compass? I had a thought. We have seen the change from 6 speed to 10 speed freewheels/cassettes. one result of this change is you don't have to get out of the saddle as much anymore . . . if at all. The only reason I get out of the saddle is for a change of postion for comfort reasons, rather than out of some necessity to get up a hill because the lowest gear I have is a 42x21. I mean now you can optimize the seated position more, because you don't have to stand on the pedals as much, if at all anymore.

another view is, I see people that ride a fixed gear on the road. They ride a track frame and fork that's design has been optimized for a flat track, so it never considered how the bike will handle when you have to get out of the saddle to get up a hill, and if you have ridden a fixie on a real long ride you know what I'm talking about because you have to ride a little different because you have to preserve your momentum to get up and over the hills. One thing you might want is a longer top tube, and a shorter stem to get your weight off the front wheel when your out of the saddle . . . (not the mention you had fork rakes of 55mm, where now it's common it have 43mm.)

If you look back at the pictures of the pro back in the 80's you will see a lot more picture where people are standing out of the pedals than they do now, Is this fact taken into the evolution bicycle frame geometry?
 

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I dunno man, you got a lot of untested assumptions and mixed variables lurking in there.

For one, I don't think standard road geometry has changed much; back in the day I seem to recall most bikes were 73/73 or so, as they are now. Maybe wheelbases are a tad shorter now, mainly because of shorter top tubes (the fashion for longer stems and lower bars), but only a cm if even that much.

Be careful with your sample selection. Just because you can find an example of an old bike that's 74 and a new bike that's 71 (and I don't doubt you can), that doesn't mean that most bikes are like that.

Granted, bikes today look considerably different. Materials and styles (aka fashion). Fork rake can be (is) fashion as well. With modern materials and a smart builder, you can build in the feel you want, even in a straight leg fork. At least that's what the magazines say and they would not lie, would they?

One thing I will agree to, seated climbing via high cadence is more common among the top riders. I watch the old tapes of Lemond or Merckx standing and grunting, it makes my knees hurt. I think that's one clear outcome of understanding power, cadence and HR together at the same time.

As far as 6 to 10 spd cassettes, it doesn't necessarily change your available gear range. People ran 13-26 back in the day just like they do now, except the jumps between were bigger. Couple with downtube shifters, and people shifted less often and therefore didn't spend so much time in the "optimal" gear. See Grant P's rants about this, not that I agree.

So, to the extent I agree with your premise, I say the causes are fashion, enabled by improved technology.

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Don't forget the transition of mountain bike design and engineering to road bikes- threadless stems, compact frames, STI, etc. All of these things have had an impact on bike design.
 

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Just a return to reason. 74 x 74 was extreme, but common in the 1980s I suppose. But would have been extreme in the 1970s and extreme now. Your baseline was an excursion that fortunately didn't last.

Let's look at a 1970s road race bike. Two schools.

1. 73 x 73, 55 x 55, 45 mm rake, 420 mm chainstays. A little longer than today's rear ends - chains weren't as flexible and the roads are pretty good today. I think I have that frame up in the shed still.

2. Slack head tube geometry. Some Italian firm used to put these out. I liked them. Head angle would be 71.5 to 72. Otherwise about the same. Use a smaller frame, longer stem, saddle back a bit. Tucks the bike under. Carves turns.

Then we entered twitch land, angels went up, folks looked to me (still on my 1974 bike) far forward and somewhat unstable.

Now we've got more or less the same choice as in the 1970s. I'll pick Specialized:

Tarmac: 54 has 54.8 cm TT. 73 head 73.5 seat. Probably steeper seat because of the 405 mm chainstay. 45 mm rake. A nice 1974 road bike with a tucked under rear end.

Roubaix 54 x 54.8. 73.5 seat 72 head. 49 mm rake, 415 mm stays. Whoopie! Somebody went to Italy and saw a bike. Look at the pro pelotons, you'll see these kinds of bike. Including the Roubaix.

It's the same basic choice. I always liked the somewhat slack headtube performance bikes.

Start stacking the old British touring bikes against the modern touring bikes. No surprises there. Let's see, I used to ride a 56 x 56 for touring, 72 parallel, stays around 435, 50 mm rake more or less. No surprise, that will still work and let someone sight see.

Now I'm on 73.5 seat 72.35 head, 54.7 TT, 405 mm stays, looks like the rake is 45 to 48. Rides JUST LIKE the Italian bikes I used to like so much. Carves turns, very secure, etc.

What caused the change? People thought steep angles were faster. They aren't, they just knock you around. So the change is to make bikes ridable for longer periods, like they used to be. New materials let the chainstays be shorter, so they are, so the seat tubes are a bit steeper, and the range of setback posts is larger so the saddle can stay in the same spot.

People still get out of the saddle to pump up things. The total range on modern racing setups isn't really much different than historically. A bigger change than more cogs is the 39T standard on chainrings. I used to tour on the widest range I could get - 42 - 52, with a wimpy 14-28. a

As to optimization of the seated position, that's been pretty well settled for quite a while. I had an expert fit me in the early 1970s. I get myself comfortable now and I'm within a few mm of that position. An optimized seated position doesn't mean you can't stand up! That's when compact frames really feel alive - out of the saddle and honking.

As to people riding fixed gears on the road. Check your history. That's how it started, see "Ordinary." Safety bikes were fixed, too. Many of us rode fixed on the road in the 1970s. Sometimes on track bikes, mostly on normal road frames. I think it's generally nuts to ride a full blown track sprint bike on the road, but it's sort of nuts to ride one on a track anyway. Fixie doesn't equal track geometry. And I generally see the same setup on a fixie as a normal road bike. Everyone I knew running fixed for the road would be on a road bike fitted the same as their usual road bike. No problem getting up the hills. If anything, I'd pick up a smaller shorter frame and run a long stem. My experience and observations of others in that day and age runs directly counter to yours.

"If you look back at the pictures of the pro back in the 80's you will see a lot more picture where people are standing out of the pedals than they do now, Is this fact taken into the evolution bicycle frame geometry?"

Who knows? Picture bias? Different style? Out of the saddle makes for great pictures! And the steep geometry then wasn't comfortable. How about the 1970s? 1960s? Earlier? The 1980s seem rather out of step.

Look back further and you'll see what I mean. Hop on a 1970s Colnago sometime. Sweet, except I have never missed the 2 x 10 Nuovo Record standard. Not that it's bad, but I like my STI brifters. I jumped from a 1974 full Campy steel bike to an STI 7 speed after 19 years - quite a jump in the components, but the handling was about the same.
 

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Creakyknees said:
For one, I don't think standard road geometry has changed much; back in the day I seem to recall most bikes were 73/73 or so, as they are now.
Mmm... not so much. I'm pretty sensitive to geometry, always have been, and I used to pore over bike geo charts 'back in the day (i.e. 80s and early 90s). 73/74 or 73.5/74 head/STA was extremely popular back then, almost obnoxiously so. Every bike was a wannabee crit bike, so it seemed. Bleah. :(

Nowadays it hasn't changed much... in my size (54cm), 73/73.5 seems to be the norm. I'd prefer parallel 73s, and thankfully, some ppl do make it.
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Cygnus said:
bikes haven't changed their basic geometry in the last century.
Eh? Bikes haven't changed their basic design in the last century (double diamond frame), but the geometry has definitely evolved over time.

Bikes for the most part used to be quite a bit shallower in the head and seat angles way back when, and longer in the wheelbase, though I'm sure one could cherry-pick a few exceptions that prove the rule.
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right. by saying basic geometry hasn't changed, i wasn't suggesting the angles are the same.

compare the bikes in the picture to most contemporary bikes (pretty similar nearly 90 years later), then constrast the cars in the pic with cars of today (perhaps not recognizable as similar objects).
 
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